1. Field of the Invention
The present invention relates generally to a computer controlled grinding machine for grinding and shaping workpieces and, more particularly, to an extremely accurate compact grinding machine controlled by a computer that writes its own programs.
2. Description of the Related Art
Grinding of workpieces into desired shapes has been desirable for hundreds of years, and as such there are many different types of grinding. Grinding operations as contemplated in the present invention may include, among others, the following operations: grinding, cut-off, lathe, two-axis grinding, OD grinding, ID grinding, turning and centerless grinding.
Centerless grinding is a well-known art useful for grinding rotatable workpieces to high precision. Conventional centerless grinding operations use a workpiece support apparatus and a grinding wheel apparatus, both of which are well-known in the art.
In conventional apparatuses, the grinding wheel apparatus typically includes a wheel spindle head which is vertically movable, i.e., movable up and down along the “y” axis, a means such as a ball or lead screw which is driven by an y-axis motor for moving the wheel spindle head, a spindle extending through and beyond the wheel spindle head, a grinding wheel mounted on the spindle, and a motor for rotating the spindle and grinding wheel.
Prior art U.S. Pat. Nos. 5,746,643 and 5,746,644 disclose numerically controlled grinding machines. Although these patents disclose useful grinding machines, they must be individually programmed for each cutting or grinding operation.
One exceptional workpiece support apparatus is disclosed in U.S. Pat. No. 5,121,571, issued Jun. 16, 1992, to Smarsh, which patent is incorporated herein by reference. The workpiece support apparatus of the Smarsh patent includes (among other beneficial components) a table, a base supported on the table, a carriage supported by the base, a horizontally-oriented spindle extending through and beyond the carriage, a regulating roller mounted on the spindle, and a means for rotating the spindle which thereby rotates the regulating roller. The regulating roller provides a rotating surface for supporting and rotating the workpiece.
Typically, the conventional regulating rollers are formed from a porous material so that micro-fine dust on the roller will not harm the friction characteristics and the workpiece may be rotated at a consistent speed. However, when the dust builds up to a point where the friction surface is too smooth to perform rolling operations, the surface must be roughened up to allow it to grip the workpiece during the grinding operation.
The table of the workpiece support apparatus is movable along a horizontal axis, or side-to-side, which will be referred to as the “z” axis. The table may be moved along the z axis by a z-axis motor which turns a belt/pulley/ball/or lead screw mechanism as is known in the art. The z-axis motor may be controlled by a conventional motion controller, such as Parker's COMPUMOTOR OEM 6200 motion controller, available from Parker Corporation of Rohnert Park, Calif.
By controlling the y-axis movement and the z-axis movement in the grinding apparatus, a workpiece may be ground as desired to meet various conformations. Current methods of controlling the y- and z-axis movement include the use of computer systems with individually written computer programs to direct the motion of the grinding apparatus. However, in these current methods, a highly-trained computer programmer writes a program template in programming language and a corresponding template in machine language so that the machine will perform based on the content of the program template. The grinding apparatus is then operated on request by running the computer program.
The accuracies with which these grinding operations may be performed is desirably as great as possible. Although the abovementioned Smarsh patent reveals a grinder capable of reproducibly grinding to several millionths of an inch, the present invention goes beyond that machine's capabilities in that the present invention can reproducibly, and nearly instantaneously achieve that result consistently. Furthermore, with the new computer programming capabilities, varying grinding operations, including dressing operations, can be performed on the same machine with minimal time being expended for the change of the routine.
It should be noted that forms can be ground into the regulating roller for various shaped parts by using the computer program and the grinding wheel of the present invention. In addition, the computer program can be used to shape or form conventional wheels with a single point diamond tool. This capability of the present machine to grind with such precision may be put to advantage in many ways, and should not be limited by the discussion within.
In conventional machines, if a variation of the computer program is desired, e.g., if it is desired to have the grinding wheel position slightly different, a completely new program needs to be written by the trained computer programmer. This is a very time consuming procedure, and must be done for each and every operation desired. Downtime is experienced while waiting for the computer programmer to intervene before the new cutting operation can be commenced.
The need to prepare individual computer programs for each operation does not lend itself well to instantaneous running by an operator. In direct contrast, the present invention discloses a computer-machine combination which writes its own programs for desired operations, and then is capable of using that new program to control the grinding machine. This saves time, money and aggravation.
Another problem which is addressed by the present invention entails a new apparatus and a new method of programming a dressing operation. One can note that after several operations of grinding, the surfaces of the grinding wheel have rough areas or uneven areas which will result in poor quality grinding. To maintain the grinding wheel surface, the grinding wheel needs to be evened out or “dressed”.
In the past, in order to dress the grinding wheel, the grinding wheel was manually positioned above a rotating dressing wheel to grind the surface of the grinding wheel. Then, the grinding wheel was repositioned above the workpiece support apparatus. When the grinding wheel was repositioned after the dressing operation, it was extremely difficult to return the grinding wheel to the exact same position relative to the workpiece support apparatus, so some accuracy is lost when this act is performed. Maintaining millionths of an inch accuracy in this scenario became nearly impossible for even the most experienced dressing operator.
In view of the above-described problems with current methods of the prior art grinding and dressing techniques, the present invention seeks to provide an easy-to-use computer system for nearly instantly constructing its own individual computer programs capable of operating various grinding apparatuses.
Another provision being sought by the present invention is an easy-to-use computer system for constructing a computer program capable of operating various grinding apparatuses, which computer system allows for easy alterations to the constructed computer program.
Yet another provision being sought is a computer system for easily, accurately, and quickly operating the dressing of a grinding wheel without removing the grinding wheel from the grinding apparatus.